Diode shunted transistor ignition system for internal combustion engines



G. O. HUNTZINGER moms SHUNTED TRANSISTOR IGNITION SYSTEM April 25, 1967 FOR INTERNAL COMBUSTION ENGINES 3 Sheets-Sheet 1 Filed Oct. 4, 1963 pril 25. 19 G. o. HUNTZINGER 3,316,445

DIODE SHUNTED TRANSISTOR IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Oct. 4, 1963 3 Sheets-Sheet 2 whim/H INVENTOR- Gezakz' 0. lz'unfzg'n e2 BY 1915 ATTORNEY P" 25, 1967 c. o. HUNTZINGER DIODE SHUNTED TRANSISTOR IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES 3 Sheets-Sheet 3 Filed Oct. 4 1963 INVENTOR.

HIS ATTORNEY United States Fatent O ice DIODE SHUNTED TRANSISTOR IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES Gerald O. Huntzinger, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 4, 1963, Ser. No. 314,059 Claims. (Cl. 315-206) This invention relates to ignition systems for internal combustion engines and more particularly to an ignition system wherein a transistor controls the current flow through the primary winding of an ignition coil.

It is well known to those skilled in the art to provide an ignition system wherein the emitter and collector electrodes of the transistor are connected in series with the primary winding of an ignition coil and wherein a device driven by the internal combustion engine controls the switching on and switching off of the transistor. In general, these systems have been of two types, one in which the conventional breaker contacts of a distributor control the conduction of a transistor, and breakerless types wherein devices such as a magnetic pick-up control the switching of the transistor. A typical system that uses breaker contacts is shown in the patent to Kirk et al., 3,046,447, whereas a breakerless system is illustrated in the patent to Short et al., 3,087,001.

The present invention is concerned with providing an improved ignition system as compared to the systems illustrated in the above noted Kirk et al. and Short et al. patents.

It has been found that in the use of transistor ignition systems, conditions are present which make it desirable to maintain a back-bias on the transistor for a short period after it has been switched off. Thus, because of high collector voltages due to the inductive load, it is desirable to maintain a back-bias on the base for a short time. This reduces the leakage currents that flow due to high collector voltages and high temperatures.

One device that improves the performance of transistor ignition systems is the use of an inductor connected across the emitter and base electrodes of the transistor as is illustrated in the Kirk et al. patent, 3,046,447. The use of the inductor does improve the performance of the ignition system, but it has been found that further improvement can be achieved by metering the energy stored in the inductor to maintain a back-bias on the transistor for a longer period of time. Thus, it has been found that if the energy from the inductor can be metered out in a relatively slow fashion, a back-bias voltage can be applied across the emitter and base electrodes of the transistor that controls primary winding current to maintain it backbiased for a longer period of time.

The device for metering the energy from the inductor can take the form of a diode connected in parallel with the inductor and this diode when connected in parallel with the inductor causes the energy of the inductor to be released in a relatively slow fashion so as to back bias the transistor for a short period of time. The use of an inductor in parallel with a diode has been suggested in the patent to De Graaf, 2,963,592, wherein the diode is used to clip transient voltages that may occur as the result of distributed capacitance and the presence of the inductor. This is in contrast to the present invention where the diode is used to control the time that a back-bias is applied to the base of the transistor for improving performance of the ignition system.

From the foregoing, it will be appreciated that one of the objects of this invention is to provide a transistor ignition system wherein the emitter and base electrodes of the transistor that controls primary winding current is shunted 3,316,446 Patented Apr. 25, 1967 by an inductance and wherein a circuit element such as a diode is provided for metering the energy out of the inductance when the transistor is biased to its nonconductive state.

Another object of this invention is to provide a transistor ignition system wherein a circuit is provided for maintaining the transistor switched off for a short interval of time after it has been biased by an engine operated device to its non-conductive condition.

Another object of this invention is to provide a transistor ignition system for an internal combustion engine wherein the emitter and base electrodes of the transistor that controls primary winding current is shunted by one winding of a two winding inductor and wherein the other winding of this inductor is connected in series with a switching device which controls conduction of the transistor connected with the primary winding of the ignition coil. With this arrangement, more energy is available in the winding that shunts the emitter and base electrodes of the transistor so that the period of back-bias for a given amount of inductance and available drive current can be extended.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein pre ferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a schematic circuit diagram of a breakerless transistor ignition system which uses a two winding inductor for maintaining the transistor which controls primary winding current turned off once an engine driven device has provided the proper signal to turn the transistor ofl.

FIGURE 2 is a schematic circuit diagram of a transistor ignition system for an internal combustion engine illustrating the use of a single winding inductor and diode for preventing premature turning on of the transistor that controls primary winding current.

FIGURE 3 is a schematic circuit diagram of a transistor ignition system which uses the breaker contacts of a conventional distributor and which has an inductor and diode connected across the emitter and base electrodes of the transistor.

Referring now to the drawings and more particularly to FIGURE 1, the reference numeral 10 designates an internal combustion engine. The engine 10 has four spark plugs 12 for firing the combustible mixture of the engine. One side of the spark plugs 12 are grounded in the usual manner and the opposite side of these spark plugs are connected with the inserts or electrodes 14 of a distributor cap designated by reference numeral 16. The spark impulses are supplied to the electrodes 14 by a rotor contact 18. The rotor contact 18 is connected with the secondary winding 20 of an ignition coil 22. This ignition coil has a primary winding 24 and it is seen that the primary winding 24 and secondary winding 20 are connected together at junction 26 and this junction is grounded.

The ignition system shown in FIGURE 1 is controlled by a voltage pulse generating device generally designated by reference numeral 28. This voltage pulse generating device has a magnetic core 30 upon which is wound a pick-up coil 32. A permanent magnet 34 is provided for causing a flow of flux through the core 30 and this flow of flux is controlled by a rotor 36 which is formed of magnetic material and which can complete and interrupt the magnetic circuit of the pulse generating device 28. As the rotor 36 rotates, pulses of voltage are induced in the pick-up coil 32 which are used to control the ignition system.

The rotor 36 and the rotor contact 18 are driven in synchronism with each other and are driven by the engine 10. This is indicated by the dotted lines connecting the engine 10 with the rotor contact 18 and the magnetic rotor 36. In practice these dotted lines can be a shaft which is driven by the engine 10 and which is mechanically coupled to both the rotor contact 18 and the magnetic rotor 36. The voltage pulse generator 28 and the distributor cap 16 can be built into one unit in which case the shaft of this unit mechanically drives both the rotor contact 18 and the magnetic rotor 36.

The ignition system of FIGURE 1 has a PNP transistor. 3 8. The collector electrode of transistor 38 is connected to one side of resistor 40. The opposite side of resistor 40 is connected to one side of primary winding 24. The emitter electrode of transistor 38 is connected with a power input conductor 42. A Zener diode 44 is connected across the emitter and collector electrodes of the transistor 38.

The power supply conductor 42 can be connected to one side of a source of direct current 44 which is illustrated as a battery. This connection is made through an ignition switch 46 which can connect one side of the battery with power conductor 42 either directly or through a resistor 48. In motor vehicle systems the source of direct current may be the generator where the generator has suflicient output to charge the battery 44.

The ignition system shown in FIGURE 1 uses another PNP transistor 50. The emitter electrode of transistor 50 is connected with a junction 52 and this junction is connected to the base electrode of transistor 38 by a conductor 54. The junction 52 is also connected to one side of a coil winding 56 which is magnetically coupled to another coil winding 58. The windings 56 and 58 form a two winding inductor or transformer, and as noted above are magnetically coupled by a magnetic core as is illustrated. The opposite side of winding 56 is connected with power conductor 42 through a resistor 60.

The collector electrode of transistor 50 is connected to one side of coil winding 58 of the two winding inductor. The opposite side of winding 58 is connected with junction 62 and a resistor 64 connects the junction 62 to ground.

The base electrode of transistor 50 is connected with junction 66. A resistor 68 is connected between the junction 66 and ground. A capacitor 70 is connected between junctions 66 and 72. A resistor 74 is connected between the junction 72 and ground- The circuit of FIGURE 1 has a third PNP transistor 76. The emitter electrode of transistor 76 is connected with junction 78 on power line 42. Junction 78 is also connected to one side of the pick-up coil 32'by means of a conductor 80. The collector electrode of transistor 76 is connected with junction 72. The base electrode of transistor 76 is connected with junction 82 which in turn' isconnected to an opposite side of pick-up coil 32 by a conductor 84. A resistor 86 connects the junction 82 and the junction 62.

The winding 56 of the two winding inductor is paralleled by a silicon diode 88 which has its cathode connected with conductor 42 and its anode connected with conductor 54. The diode 88 is therefore connected in parallel with the emitter and base electrodes of transistor 38 and is connected in parallel with the coil 56 of the two winding inductor.

When using the system of FIGURE 1 the power conductor is connected directly to the battery 44 when the engine is being cranked to start it and is connected to the power conductor 42 through the resistor 48 when the engine is running. It can be seen that the current flowing through primary winding 24 will depend upon the conduction or non-conduction of transistor 38. Thus, when transistor 38 is turned on in its emitter-collector circuit current can flow from power conductor 42, through the emitter-collector circuit of transistor 38 and then through the primary winding 24 to ground. When transistor 38 is turned off in its emitter-collector circuit the circuit to the primary winding 24 is broken and a large voltage is then induced in the secondary winding 20 which is applied to a spark plug 12, through rotor 18, through a distributor cap electrode 14 and then through a conductor connecting one of these electrodes to one of the spark plugs 12.

The conduction of transistor 38 depends upon the conduction of transistor 50. Thus, when transistor 50 is switched on in its emitter-collector circuit there is a path for base current for transistor 38 which is through conductor 54, through the emitter-collector circuit of transistor 50, through winding 58 of the two winding inductor and then through the resistor 64 to ground. When transistor 50 switches off in its emitter-collector circuit, the transistor 38 is likewise switched off since at this time the junction 52 has a voltage which is sufficiently positive to turn off transistor 38.- Both transistors 38 and 50 are biased to conduct by batttery 44 when switch 46 is closed.

The conduction of transistor 50 is controlled by the conduction of transistor 76. With no signal voltage induced in the pick-up coil 32, the transistor 76 is biased to a non-conductive condition. When a signal voltage is induced in the pick-up coil 32 of the proper polarity, the transistor 76 is biased to a conductive condition and will therefore conduct between its emitter and collector electrodes. With transistor 76 conductive in its emittercollector circuit, the capacitor 7 0 is substantially connected across the emitter and base electrodes of transistor 50. This capacitor will have previously accumulated a charge due to base current flowing from transistor 50, through capacitor 70 and through resistor 74 to ground when the transistors 38 and 50 were both biased to a conductive state by the battery 44. The charge on the capacitor therefore drives the transistor 50 to a non-conductive condition and since the transistor 38 follows the conduction or nonconduction of transistor 50, it will be driven non-conductive to cause a spark impulse to be de veloped. The operation of transistors 38, 50 and 76 is explained in greater detail in the Short et al. patent, 3,087,001.

It will be appreciated that when transistors 38 and 50 are biased to a conductive condition, as when no signal voltage is induced in pick-up coil 32, current will flow from power conductor 42, through resistor 60, through coil winding 56, through the emitter and collector electrodes of transistor 50, through coil winding 58 and then through resistor 64 to ground. When transistor '50 goes non-conductive, as when a voltage is generated in pickup coil 32 the circuit for both windings 56 and 58 is broken. A voltage now appears across the coil winding 56 which is positive at junction 52 and negative at the connection of winding 56 and resistor 60. This voltage is of the correct polarity to aid in driving the transistor 38 non-conductive since it drives the base electrode of transistor 38 positive. The energy is metered out of the coil winding 56 in a relatively slow fashion by the provision of the diode 88 which will conduct current as a result of the voltage induced in the coil winding 56. The diode 88 also provides a clamping action in that it limits the reverse voltage applied to the base and emitter of transistor 38. This action performs two beneficial functions, the first being that the transistor 38 is protected from a reverse breakdown between its base and emitter. The other beneficial function is that by utilizing the diode 88, the reverse voltage is maintained on the transistor 38 for a longer period of time as compared to an arrangement where no diode is utilized such as that disclosed in the above-mentioned Kirk et al. patent. The reverse bias is maintained for a longer period of time because the time required for the release of energy from the inductor 56 is an inverse function of the amount of voltage across the inductor 56 at the instant that the transistor 50 is driven nonconductive. Since this voltage is reduced by the provision of the diode 88, the time required for the inductor to release all of its energy is increased to therefore hold the transistor 58 nonconductive for a longer period of time as compared to a system that does not have a diode. This causes the transistor 38 to be biased to a non-conductive condition for a longer period of time as compared to a system where no means such as diode 88 were provided for metering out the energy in a slow fashion from coil winding 56. As a result the performance of the ignition system is improved as oompared to an arrangement wherein only an inductance is used as shown in the above mentioned Kirk et al. patent. It will be appreciated that the voltage induced in winding 56 when transistor 50 switches oif is the additive effect of current passing through winding 56 when transistor 50 was on and the transformer action of the two winding inductor.

Referring now to FIGURE 2, a modified ignition system is illustrated which has a single winding inductor and diode combination shunting the emitter and base electrode of the transistor that controls primary winding current. In FIGURE 2, the same reference numerals have been used as were used in FIGURE 1 to identify identical parts in each figure. The FIGURE 2 system differs from the one of FIGURE 1 in that a single winding inductor having an inductance of approximately millihenries is connected across the emitter and base electrode of transistor 38. The inductor 90 is shunted by a silicon diode 92.

The system of FIGURE 2 also differs from the one shown in FIGURE 1 in that a capacitor 94 is connected across the resistor 40 and primary winding 24. The system of FIGURE 2 also uses capacitors 96 and 98 which are not illustrated in FIGURE 1.

The operation of the system shown in FIGURE 2 is identical with the operation of the system shown in FIGURE 1 in that transistors 38 and 50 are normally biased to a conductive condition by the source of direct current 44, but are switched off when transistor 76 is switched on by a voltage being induced in the pick-up coil 32. In FIGURE 2, energy is built up in the inductor 90 when transistor 50 is switched on in its emitter-collector circuit in the same manner that energy is built up in coil winding 56 shown in FIGURE 1. This energy is metered out by diode 92 when transistor 50 is driven non-conductive. The system of FIGURE 2 does not obtain the benefit of current flowing from the collector electrode of transistor 50 as is the case in FIGURE 1 wherein inductor 56 is magnetically coupled to inductor 58 which has collector current flowing through it. Thus, in the system of FIGURE 1 base current from transistor 38 will flow through the emitter and collector of transistor 50 and will also flow through the coil winding 58 so that in FIGURE 1 more energy can be developed in coil winding 56 as compared to the FIGURE 2 situation where only a part of the emitter current of transistor 50 flows through the inductance 90.

From the foregoing it is seen that the system of FIG- URE 1 provides a greater improvementrin maintaining the transistor 38 turned off as compared to the system of FIGURE 2 although the system of FIGURE 2 provides an improvement as compared to systems that only use an inductor such as shown in the Kirk et al. patent noted above.

Referring now to FIGURE 3, an ignition system is illustrated that is controlled by the conventional breaker contacts of a distributor and which has an inductor-diode combination of the same type that is illustrated in FIG- URE 2. In FIGURE 3, the same reference numerals have been used as were used in FIGURE 1 to identify identical parts in each figure.

In FIGURE 3 the conduction of the PNP transistor 100 is controlled by breaker contacts 102 and 104 found on a conventional distributor. The breaker contact 102 6 is carried by a breaker lever 106 which is electrically connected with conductor 108. The fixed breaker contact 104 is grounded. The breaker lever 106 which carlies the breaker contact 102 is moved by a cam 110 that causes the breaker contacts 102 and 104 to open and close. The breaker lever 106 in a conventional manner is spring biased to a position where contacts 102 and 104 are engaged and these contacts are periodically separated by the cam 110.

In the system of FIGURE 3 the breaker cam 110 and the rotor contact 18 are driven by the engine 10 as designated by the dotted lines. In actual practice a conventional distributor will have both a rotor contact 18 and the breaker contacts 102 and 104 built into one unit which is shaft driven from the enginne 10. This distributor can have the usual vacuum and centrifugal advance mechanisms.

In the system of FIGURE 3 the emitter and base electrodes of transistor are shunted by the single winding inductor 112 and the silicon diode 114. The Zener diode 44 shunts the emitter and collector electrodes of transistor 100 and a resistor 116 is connected between the base electrode of transistor 100 and conductor 108.

When the breaker contacts 102 and 104 in FIGURE 3 are closed base current for transistor 100 can flow from power conductor 42, through the emitter-base circuit of transistor 100, through resistor 116, through conductor 108 and through the closed breaker contacts 102 and 104 to ground. With base current flowing in transistor 100 the transistor 100 turns on in its emitter-collector circuit and current can now flow from conductor 42 through the emitter-collector circuit of transistor 100 and then through the primary winding 24 to ground.

When breaker contacts 102 and 104 open the base circuit for the transistor 100 is opened and the transistor will be biased to a non-conductive state in its emitter-collector circuit. When transistor 100 turns off the circuit is open to the primary winding 24 and a large voltage is therefore induced in the second winding 20 which is applied to one of the spark plugs 12 by rotor contact 18, one of the distributor cap electrodes 14 and the conductor connected with one of the spark plugs 12.

During the time that breaker contacts 102 and 104 are closed, current can flow from the positive power conductor 42, through inductor 112, through resistor 116 and then through breaker contacts 102 and 104 to ground. When the breaker contacts 102 and 104 open, the circuit for inductor 112 is opened and a voltage is now developed in this inductor which is positive on conductor 118 and negative on conductor 42. This voltage causes a current to flow through diode 114 and therefore a voltage exists for a predetermined length of time which drives the base of transistor 100 positive and raises the potential of the base sufiiciently to maintain the transistor 100 turned off for a length of time following the opening of the breaker contacts 102 and 104. The diode 114 like diodes 88 and 92 in FIGURES 1 and 2 slowly meters the energy from the inductance 112 to prevent the transistor 100 from being switched back on too fast by transient voltages.

The two winding inductor arrangement of FIGURE 1 has been disclosed for use with a breakerless system but it will be appreciated by those skilled in the art that this system is also applicable to breaker type systems of the type shown in FIGURE 3. Thus, it would be possible to provide an inductor in the system of FIGURE 3 which would have another winding magnetically coupled with winding 112 and connected between resistor 116 and breaker contact 102.

From the foregoing, it can be seen that all of the embodiments disclosed have the common feature of providing an inductance and diode which parallel the emitter and base electrodes of the transistor that controls primary Winding current. In each case, the diode is used to meter the energy from the inductance to insure that the transistor that controls primary winding current is biased to a non-conductive state by the voltage developed in the inductance for a length of time following the production of an engine synchronized signal which switches the transistor off. The diode therefore has the function of increasing the turn off time of the transistor as compared to the situation where only an inductance is used such as in the Kirk et al. patent mentioned above.

While the embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

I claim:

1. An ignition system for an internal combustion engine comprising, a plurality of sparkdischarge devices for igniting the combustible mixture of said engine, an ignition coil having a primary winding and a secondary winding, rotatable spark distributing mens connecting said secondary winding with said spark discharge devices, 8.

transistor having emitter, collector and base electrodes, a source of direct current, a circuit for energizing said primary winding connected across said source of direct current including said primary winding and the emitter and collector electrodes of said transistor, a switching means operated in synchronism with said engine and driven in synchronism with said rotatable spark distributing means, means connecting said switching means between the base electrode of said transistor and a first side of said source of direct current, an inductor separate from said ignition coil, means connecting said inductor between one side of said switching means and a second side of said source of direct current, said inductor being connected across the emitter and base electrodes of said transistor, and a diode connected in parallel with said inductor having an anode connected with the base electrode of said transistor and a cathode connected with the emitter electrode of said transistor said inductor developing a voltage of self-induction which biases said transistor nonconductive when said switching means is nonconductive, the energy received by said inductor from said source of direct current when said switching means is conductive being released through said diode when said switching means is nonconductive.

2. The ignition system according to claim 1 wherein the switching means that is operated in synchronism with the engine is a pair of cam operated breaker contacts.

3.The ignition system according to claim 1 wherein the switching means that is operated in synchronism with the engine is a second transistor.

4. The ignition system according to claim 1 wherein the switching means that is operated in synchronism with the engine is a transistor which has its conduction controlled by a voltage pulse generating means driven by the engine.

5; An ignition system for an internal combustion engine comprising, a plurality of spark discharge means for said engine, an ignition coil having a primary winding and a secondary winding, a spark distributing means driven by said engine connecting said secondary winding and said spark discharge means, a transistor having emitter, col-' lector and base electrodes, a source of direct current, means connecting said primary winding and the emitter and collector electrode of said transistor across said source of direct current, an inductor having first and second magnetically coupled windings, a three terminal switching means having a pair of current carrying terminals and a control terminal, means connecting said first winding between one side of said source of direct current and one of said current carrying terminals, means connecting said second winding of said inductor between an opposite side of said source of direct current and said other current carrying terminal, means connecting one of said current carrying terminals with the base elec trode of said transistor, a diode connected across said first Winding of said inductor and means connected with the control terminal of said three terminal switching means controlling the conduction of said three terminal switch means in synchronism with operation of said engine.

6. The ignition system according to claim 5 wherein the three terminal switching means is a transistor.

7. The ignition system according to claim 5 wherein the three terminal switching means is controlled by a voltage pulse generating means driven by the engine.

8. An ignition system for an internal combustion engine comprising, a plurality of spark plugs for said engine, an ignition coil having a primary winding and a secondary winding, a spark distributing means having an element driven by said engine connecting said secondary winding with said spark plugs, a transistor having emitter, collector and base electrodes, a source of direct current, means connecting the emitter and collector electrodes of said transistor and said primary winding across said source of direct current, breaker contacts opened and closed in synchronism with said engine and operating in synchronism with said spark distributing means, an inductor separate from said ignition coil, means connecting said inductor between one of said breaker contacts and a first side of said source of direct current, said inductor being connected in parallel with the emitter-base circuit of said transistor, a diode connected across said inductor and across the emitter-base circuit of said transistor, said diode being poled such that its cathode is connected with said first side of said source of direct current, and means connecting said breaker contacts between the base electrode of said transistor and a second side of said source of direct current, said breaker contacts when closed, providing a path for base current for said transistor and also providing a current path for current flowing through said inductor, said breaker contacts when open opening the circuit for said inductor and opening the base circuit of said transistor, said inductor developing a voltage of selfinduction which biases said transistor nonconductive when said breaker contacts are open, the energy received by said inductor from said source of direct current when said breaker contacts are closed being released through said diode when said breaker contacts are open.

9. The ignition system according to claim 8 wherein a resistor is connected between the base electrode of the transistor and one side of the pair of breaker contacts.

10. The ignition system according to claim 8 wherein one of the breaker contacts is connected directly to ground and wherein the other of the breaker contacts is connected to the base electrode of the transistor through a resistor.

References Cited by the Examiner UNITED STATES PATENTS 2,963,592 12/1960 De Graaf 307-88.5 3,016,477 1/ 1962 Naborowski 315209 3,046,447 7/ 1962 Kirk 315-209 3,051,870 8/1962 Kirk 315-206 3,056,066 9/1962 Dozier 315-224 X 3,087,001 4/1963 Short 315206 3,135,878 6/1964 Eagle 30788.5 3,162,790 12/1964 Wakamatsu 30788.5 3,169,212 2/1965 Walters 315209 3,196,313 7/1965 Quinn 315219 JAMES W. LAWRENCE, Primary Examiner.

ROBERT SEGAL, GEORGE N. WESTBY, S. D.

SCHLOSSER, Assistant Examiners. 

1. AN IGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING, A PLURALITY OF SPARK DISCHARGE DEVICES FOR IGNITING THE COMBUSTIBLE MIXTURE OF SAID ENGINE, AN IGNITION COIL HAVING A PRIMARY WINDING AND A SECONDARY WINDING, ROTATABLE SPARK DISTRIBUTING MENS CONNECTING SAID SECONDARY WINDING WITH SAID SPARK DISCHARGE DEVICES, A TRANSISTOR HAVING EMITTER, COLLECTOR AND BASE ELECTRODES, A SOURCE OF DIRECT CURRENT, A CIRCUIT FOR ENERGIZING SAID PRIMARY WINDING CONNECTED ACROSS SAID SOURCE OF DIRECT CURRENT INCLUDING SAID PRIMARY WINDING AND THE EMITTER AND COLLECTOR ELECTRODES OF SAID TRANSISTOR, A SWITCHING MEANS OPERATED IN SYNCHRONISM WITH SAID ENGINE AND DRIVEN IN SYNCHRONISM WITH SAID ROTATABLE SPARK DISTRIBUTING MEANS, MEANS CONNECTING SAID SWITCHING MEANS BETWEEN THE BASE ELECTRODE OF SAID TRANSISTOR AND A FIRST SIDE OF SAID SOURCE OF DIRECT CURRENT, AN INDUCTOR SEPARATE FROM SAID IGNITION COIL, MEANS CONNECTING SAID INDUCTOR BETWEEN ONE SIDE OF SAID SWITCHING MEANS AND A SECOND SIDE OF SAID SOURCE OF DIRECT CURRENT, SAID INDUCTOR BEING CONNECTED ACROSS THE EMITTER AND BASE ELECTRODES OF SAID TRANSISTOR, AND A DIODE CONNECTED IN PARALLEL WITH SAID INDUCTOR HAVING AN ANODE CONNECTED WITH THE BASE ELECTRODE OF SAID TRANSISTOR AND A CATHODE CONNECTED WITH THE EMITTER ELECTRODE OF SAID TRANSISTOR SAID INDUCTOR DEVELOPING A VOLTAGE OF SELF-INDUCTION WHICH BIASES SAID TRANSISTOR NONCONDUCTIVE WHEN SAID SWITCHING MEANS IS NONCONDUCTIVE, THE ENERGY RECEIVED BY SAID INDUCTOR FROM SAID SOURCE OF DIRECT CURRENT WHEN SAID SWITCHING MEANS IS CONDUCTIVE BEING RELEASED THROUGH SAID DIODE WHEN SAID SWITCHING MEANS IS NONCONDUCTIVE. 